A variety of image forming apparatuses are currently available, including printers, copiers, facsimile machines, plotters, and multifunctional machines including functions of printers, copiers, and facsimile machines.
Among such image forming apparatuses, there are some image forming apparatuses that include a liquid ejecting device with a recording head. The liquid ejecting device may use the recording head to eject or spray a droplet or droplets of liquid including recording fluid onto a recording medium to form, record, or print an image while a sheet conveying member is conveying the recording medium.
A recording medium is hereinafter referred to as a “recording sheet.” The recording sheet may be formed of any material such as paper.
Recording fluid is hereinafter referred to as “ink”, when required.
Liquid that can be ejected or sprayed by a liquid ejecting print head includes recording fluid or ink, liquid resist, DNA samples, patterning materials, and so forth.
In response to recent demands for speeding up image forming operations, the number of high-speed image forming apparatuses is increasing.
For further increasing operation speed, image forming apparatuses may employ a line-type print head in which a distance in its longitudinal direction is equal to a width of a recording sheet.
In some instances, it may be difficult however, to form such line-type print head in one shape because of variations, yield, cost, and so forth.
As an alternative to the above-described print head having a long width in one shape, there are techniques for employing a line-type print head in which a plurality of print head units having a short distance in the longitudinal direction are aligned in a zigzag manner.
In one of the techniques, an image forming apparatus including a plurality of print head units can be used. Each print head unit may include nozzle arrays of the same number of ink colors. Respective ink droplets of the respective ink colors may be ejected from nozzle orifices of the nozzle arrays. The plurality of print head units may be aligned in a zigzag manner to form a line-type print head.
In some of the techniques, a group formed by a plurality of print head units for each single color may be aligned in a zigzag manner. By arranging the group of print head units according to the number of ink colors, a line-type print head may be formed.
There is another technique in which a group formed by a plurality of print head units for each single color may be aligned in a zigzag manner. In this technique, the group of print head units may be arranged corresponding to the number of colors of ink to form a line-type print head, so that a flexible print circuit or FPC that can serve as a wiring member can be installed from each of the plurality of print head units to be connected to both sides of the line-type print head.
In a different one of the techniques, a group formed by a plurality of print head units including nozzle orifices for four colors may be arranged in a zigzag alignment to form a line-type print head in a long shape.
Another one of the techniques arranges two print head tips aligned in a zigzag manner. Groups of the two print head tips corresponding to the number of colors of ink (in this technique, four colors) are aligned to form one print head unit. Further, a line-type print head may be formed by a plurality of print head units.
In a related art image forming apparatus including a liquid ejecting device, quality in a color image may significantly vary and depend on accuracy of positions at which each droplet of respective colors of ink lands onto a recording medium. To obtain high accuracy in landing positions of respective colors of ink, each nozzle of a print head unit included in the liquid ejecting device has high positional accuracy.
For enabling the above-described positional accuracy, the liquid ejecting device has a nozzle array, which is a series of nozzle orifices. That is, the nozzle array includes a plurality of nozzles according to the same number of colors of ink, and the plurality of nozzles for each color of ink are located in respective accurate positions in one print head unit. With the above-described configuration, the landing position of each droplet of color ink can be highly accurate.
Therefore, with a configuration in which a plurality of print head units, each of which including line-type print heads, it is preferable, for forming or creating high quality images, that one print head unit includes nozzle arrays having a plurality of nozzles according to the same number of colors of ink.
In this case, if a droplets of each color ink lands onto a recording sheet in a wrong order, printed images may have different color tones and may cause non-uniformity or unevenness, which results in deterioration in image quality.
To avoid the above-described drawback, it is preferable that print head units are aligned in an identical order with respect to each color so that droplets of respective colors of ink can lands in a same order.
Thus, a plurality of print head units including a plurality of nozzle arrays can be arranged in a first direction (i.e., a width direction of a recording sheet) and aligned in a zigzag manner in a second direction that is different from the first direction, and a line-type print head can be formed.
In this case, a signal that can activate an energy generating element may need to be sent to each print head unit. The energy generating element generates energy that can cause a corresponding nozzle of respective nozzle arrays in each print head unit to eject or spray a droplet of each color ink.
In this case, as shown in one of the above-described technologies, a FPC for supplying electrical signals may be provided from each of the plurality of print head units and connected to two opposite sides of the line-type print head.
When the above-described configuration is applied, a wiring pattern for each color in the FPC may vary on the two opposite sides of the line-type print head.
A control board that connects the FPC to the opposite sides of the line-type print head may can be provided for each side to be connected to the FPC, but such a configuration causes an increase in cost.